Production of rayon



Sept. 23, 1947. n K. M. MCLELLAN 2,427,993

PRODUCTION OF RAYON Filed July 26,, 1944 Ta 59 58 54 1? a in 52 g 46 48355 f as: 6% 47 llllHll I l illllH iNVENTOR minim? Us MELeZlmm BYATTORNEY atented Sept. 23,194?

PRODUCTION OF RAYQN Kenneth M. McLellan, Cleveland, Ohio, assignor toIndustrial Rayon Corporation, Cleveland, Ohio, a corporation of DelawareApplication July 25, 1944, Serial No. 546,516

1 This invention relates to the production of rayon thread or yarn ofhigh tensile strength and it provides a new and improved process bywhich such rayon may be advantageously produced.

High strength rayon yarns or threads may be produced by a variety ofmethods. In producing viscose rayon high strength yarns, it is commonpractice to extrude a viscose solution into a coagulating bath andthereafter subject the incompletely regenerated viscose rayon to one ormore stretching operations. Prior to or during the stretchingoperations, the thread may be treated with various liquids in order tomake it more plastic so that it may be stretched more readily.Nevertheless, in stretching the thread, tensions are built'up which tendto resist the Stretching forces.

over guides in passingirom one stretchingdevice to another and bycontractive force applied to the yarn stretching devices as a result ofthe shrinking tendency of the yarn passing over them.

Thus, for example, in producing viscose rayon by the continuous process,newly formed viscose thread is withdrawn from a coagulating bath by athread-advancing, thread-storage reel on a continuous processingapparatus such as that shown and described, for'example, in TorrencePatent No. 2,284,497. The thread is thereafter advanced to a series ofthread-advancin thread-storage 8 Claims. (CI. 18-54) Such tensionsmanifest themselves by increased abrasive wear when the yarn is passedon the operating portions of the thread-advancing reels may be such asto impose unduly excessive strains on the bearing structures whichsupport these portions of the reel. Similarly, when high stretch isimparted to the yarn, the pressure exerted by the yarn on the threadguides over which it passes in advancing from one reel to the other maybecome so great as to result in damage to the filaments.

This invention provides a method by which the tensions resulting fromthe stretching of the yarns or threads may be efiectively minimizedwithout reduction in tensile strength of the final yarn product. Ingeneral, this is accomplished by stretching the incompletely regeneratedthread in at least two steps, the latter stretching step preceded by atreatment with an aqueous plasticizing medium, then permitting thestretched thread to shrink by an amount substan' tially less than it wasstretched and thereafter completing the regeneration of the threadwithout permitting substantially any further shrink-e age thereof. Inthe viscose process this may be accomplished particularly effectively bystretching the incompletely regenerated thread a total of at least 50%,and permitting the thread to shrink no more than about 5% after whichthe regeneration of the thread is completed.

devices upon which a, variety of processing operations may be performed.In order to stretch the thread to increase its tensile strength, thereels may be operated at various peripheral speeds so that the thread inpassing from one reel to the next succeeding reel is subjected to adesired amount of stretch, If desired, flared reels such as those shownin Torrence Patent No. 2,266,574 may be used to perform the stretchingoperation.

The tension built up in the thread as a result of the stretchingoperation causes the thread to tend to contract, and when the thread iswrapped around the thread-advancing reel it exerts substantial pressureon the operating members of the reel. The thread is advanced on the reelas a. result of the inclined and offset relationship of the axes of itstwo interdigitating cage members. 2,210,914.) If the yarn is tightlywrapped around the cage members, increased abrasive wear of thefilaments will be produced and the possibility of breakage of some ofthe filaments in the thread is increased. Where the amount of stretchim-' parted to the yarn is very considerable, e. g., 50%

In the further description of the invention,

reference will be made to the production of rayon by the continuousprocess on an apparatus such as that shown and described, for example,in Torrence Patent No. 2,284,497. In this connection, reference will bemade to the accompanying drawings in which:

Figure 1 showsa portion of a continuous rayon processing apparatus;

Figure 2 shows a sectional plan view of a particular type ofthread-advancing, thread-storage reel which may be used in practicingthe invention; and

Figure 3 shows an end view of the reel structure illustrated by Figure2.

(See, for example; Knebusch Patent No.

Referring now to Figure 1, a viscose solution is pumped -through masstube I! and extruded through spinneret l8 into an acid coagulating bathIS in trough ill. The newly formed and incompletely regenerated viscosefilaments are then led in the form of a thread bundle upwardl throughwiper guide 2! which removes excess coagulating bath from the thread andthen onto a rotating thread-advancing, thread-storage reel l l ofuniform diameter. The thread advances'in a plurality of helical turnsfromv the supported to the unsupported end of the reel and then passesdownwardly through a second wiper guide 22 which also aids in removingprocessing liquid from the thread. The thread thereafter passes overguides 23 and 24 onto a second thread-advancing, thread-storage reel I2of uniform diameter.

This reel is rotated at a higher peripheral speed than thethread-advancing reel H by means of drive shaft 48 and bevel gears 4iand 42, the latter of which are mounted on reel shaft 43. As a result ofthe difference in peripheral speeds between reels II and I2, theincompletely regenerated thread is stretched. While the thread is on theThe bars 41 of reel member 45 are fixed to a genreel l2 it is treatedwith a liquid, e. g., warm water or the like, which tends to plasticizethe thread. This liquid is piped through conduit 26 and dischargedthrough the outlet 21. The liquid which drips from reel I2 is collectedln'the trough 30 below the thread-advancing reel.

The plasticized thread after being discharged from the thread-advancingreel l2 passes over guide 3! and onto thread-advancing reel l3. .The

portion of reel I3 nearest the supported end is of uniform diameter andthe portion of the reel nearest the unsupported end is also of uniformdiameter but the diameter is less than thatof the first portion. Thesetwo portions are joined by a tapered section which merges into the twoportions of unequal diameter as shown more fully in Figure 2. The reelI3 is driven by means ordrive shaft 48 and-bevel gears 4i and 42, thelatter of which is mounted on reel shaft 43. llhe speed of rotation ofreel i3 is such that the peripheral speed of the portion of greatestdiameter is greater than that of the preceding reel l2 so that a stretchimparted to the thread in passing from reel l2 to reel l3. The thread inadvancing from the supported to the unsupported end of reel i3 is'permitted to shrink when it passestover the tapered portion of the reeland the shrinkage is then checked when the thread reaches the portion ofthe reel of smallest diameter. While the thread is on the reel l3,'it istreated with a suitable processing liquid to complete the regenerationof the thread. This liquid may advantageously be in the form of an acidsolution which drips onto to reel through the pipe 32. The constructionand operation of reel [3 is such that the peripheral speed of theportion of the .reel of smallest diameter is greater than the peripheralspeed of the preceding reel l2.

After being discharged from reel l3, the thread passes over guide 34 andonto a thread-advancing reel M of uniform diameter. This reel isoperally cylindrical body portion '49. Reel member 45 is concentricallymounted by means of hub 50 on-reel drive shaft 43 journaled in thesupporting member 53.

The other reel member 46, which may be termed the eccentric reel member,has its bars 48 formed as part of a rigid, cagelike member-52. The bars48 are fixed at the unsupported end of the reel to an internal annularreinforcing rib 55 which serves to impart rigidity to the bars. At theother end of the member 52, the bars 48 merge into an externalannular-rib or fiange 54 which also imparts rigidity'to the bars andserves as a means byv which the cagelike member 52 is fixed 'to therotatable annular supporting flange 58.

.The cagelike' member 52 is rigidly. fixed to flange 58 by means of anut and bolt assembly 59'. The flange 58 is part of the hub 68 which ismounted for rotation on antifriction bearings shaft 43 rotates.

erated by means of drive shaft 48 and bevel gears 4l, 42 at the sameperipheral speed as that prevailing on the portion of reel l3 which isof smallest diameter. Consequently, no streach will be imparted to thethread in its passage from reel l3 to reel 14. While the thread is onreel i4, it is treated with -additional processing liquids to furthercomplete the regeneration of the thread. These liquids are applied to.the thread by being discharged through the pipe 32. Excess processingliquids are collected in the troughs 38 under the respective reels.

After leaving the reel l4, the thread is subjected to further processingoperations such as, for example, desulfurizing, drying, and the like inorder to make the final rayon product.

To further illustrate one form of apparatus which may be used withadvantage in practicing the invention,-reference will now be made to thethread-advancing, thread-storage reel shown in some detail in Figures 2and 3. The reel consists .of two rigid interdigitatingcorrosion-resistant IBI positioned on the nonrotating eccentric sleeve53. The eccentric sleeve, in turn, is mounted on a bushing type bearing62 within which the reel The corresponding bearing members atthesupported end of the reel structure are not shown. Y

- Because of the offset and skew relation of the axes of the two reelmembers, a thread wound about the reel during rotation thereof is causedto advance in spaced, generally helical turns along the length of thereel.

As illustrated in Figure 2,,the reel has a composite thread-bearingperiphery comprising two generally cylindrical portionsof uniformdiameter AB and CD, the latter being-of less diameter than the formerand disposed at the discharge end of the reel. Merging with saidcylindrical portions is an intermediate portion- BC having regularlydiminishing diameters which decrease from the end of zone AB to thebeginning of zone CD.

If the tensions built up in the thread as a result of'the stretchingoperations become sufiiciently great, they may interfere with the properadvancement of the thread on the thread-advancing reel. Thus, as aresult of the tension, the offset and inclined relationship of the reelmembers may tend to be changed so that the thread is no longer properlyadvanced onrthe reel members.

' Similarly, the force applied to the reel members due to the tension ofthe thread may also impose substantialstrains on the bearings supportingthe reel members. Additionally, the bundle of filaments constituting thethread may be substantially flattened because of the tension in thethread with the result that overlapping of thread turns may occurcausing filament damage. Furthermore, the processing liquids applied tothe thread while it is on the reel may have greater .difliculty ineffectively penetrating the thread that illustrated in Figures 1 and 2in the position shown at It in Figure 1 efiectively minimizes suchdifficulties. The tension built up in the thread as a result of thestretching operations between reels II and I2, and I2 and I3,respectively, is substantially reduced when the thread is advanced overthe tapered portion 3-0 (Figure 2 The thread, consequently, is permittedto shrink somewhat and thereafter is advancedIon the reel under reducedtension. Due to relaxed tension in the thread, the strains imposed onthe reel members and their associated parts are substantially reducedand the processing liquids applied to complete the regeneration of thethread may act more effectively in accomplishing their intended purpose.

The invention will be more fully described by referring to the followingexampl but it is understood that the invention is not limited thereto.

Example 1100 denier 480 filament viscose rayon is produced by extrudinga viscose solution containing about 7-8% of cellulose and about 6-7% ofcaustic soda through a suitable spinneret into a coagulating bathcontaining about 89% of sulfuric acid, about 20% of sodium sulfate andabout 3.4- 3.8% of zinc sulfate. The newly coagulated but incompletelyregenerated thread is withdrawn 6 "thread on the reel H as illustratedin Figure 1 and. a small number of turns on reel l2", it may bedesirable in certain instances to modify these conditions so that thenumber of turns on these 7 5 reels may be more nearly equal. This willdepend ous solutions of suitabl plasticizing agents. The

processing liquids applied on reels i3 and it to complete theregeneration of the thread are advantageously such that they containless acid 0 than is contained in the coagulating bath and from thecoagulating bath by means of a thread- .reel. Due to the difference ofperipheral speeds between reels II' and i2, the thread will be stretchedapproximately 24.5%. Water at a temperature of about 58 C. drips throughthe pipe 21 onto the thread layer on reel 02 to plasticize the thread.

The thread is conducted from reel i2 to reel i3 which has athread-bearing periphery of maximum diameter at its supported end ofabout 5.75 inches. The reel is rotated at a rate such that this portionof its periphery has a peripheral speed of approximately 80.8 meters perminute. As a consequence, the thread will be given additional stretch sothat the total stretch imparted to the thread will be approximately54.8%. The tapered portion of the reel is such that the thread they may,if desired, be in the form of a diluted solution of the coagulatingliquid.

Although the foregoing description of the invention has been chieflyconcerned with the production of viscose rayon filaments, it is to beunderstood that the invention may also be applied to the production ofother types of regenerated cellulosic products, whether made by theviscose or cuprammonium methods. Among such products may be mentionedthreads, bands, ribbons and the likewhere similar problems of hightensions due to stretching operations may be encountered.

I claim:

1. A process for the manufacture of viscose rayon which comprisesextruding a viscose solution into an acid coagulating bath, withdrawingthe resulting viscose filaments from said coa lating bath before theyare completely regener-' ated, stretching said incompletely regeneratedfilaments, treating said filaments with a dilute:

aqueous acid solution but maintaining said filaments in an incompletelyregenerated state,

0 without permitting substantially any further is permitted to shrinkabout 4% and thereafter the thread is advanced on the portion of thereel of minimum but uniform diameter which is traveling at a peripheralspeed of about 77.6 meters per minute. While the thread is on this reel,it is treated with a processing liquid containing about 2.5% ofvsulfuric acid and about 3.5% of sodium sulfate to complete regenerationof the thread. After completing its travel on reel I3, the thread isadvanced to reel M which operates at the same peripheral speed as thedischarge end of reel i3. Consequently, no further stretch is impartedto the thread. Thereafter, the thread is subjected to further processingoperations to complete the transformation into a finished raythread hashigh tenshrinkage.

2. A process for the manufacture of viscose rayon which comprisesextruding a viscose'solution into' an acid coagulating bath; withdrawing.the resulting viscose filaments from said bath before they arecompletely regenerated; stretching said incompletely regeneratedfilaments; treating said filaments with an aqueous plasticizing mementswhilethey are in an incompletely regenfilaments without permittingsubstantially any further shrinkage. 3. A process for the manufacture ofviscose rayon which comprises'extruding a viscose solution into an acidcoagulating bath; withdrawing the resulting viscose filaments from saidbath before they are completely regenerated; stretching saidincompletely regenerated filaments: treating said filaments with anaqueous plasticizing medium; stretching said treated filaments a 7second time; treating said stretched filaments 7 with dilute aqueousacid solution but maintaining said filaments in an incompletely regener-4. A process for the manufacture of viscose rayon which comprisesextruding a viscose solution into an acid coagulating "oath; withdrawingthe resulting viscose filaments from said bath be-. fore they arecompletely regenerated; stretching said incompletely regeneratedfilaments; treating said filaments with an aqueous plasticizing mediumwhile maintaining them in said stretched condition; stretching saidtreated filaments a second time; treating said stretched filaments witha dilute aqueous acid solution but maintaining said filaments in anincompletely regenerated state; permittingsaid incompletely regeneratedfilaments to shrink an amount less than the amount of said secondstretch; and thereafter treating said partially shrunk filaments with anacid regenerating solution and completing the regeneration of saidfilaments without permitting substantially any further shrinkage.

5. The process as in claim 4 in which the total stretch imparted to saidfilaments as a result of said first and second stretching steps is atleast 50% and inwhich said partial shrinkage of said filaments is nogreater than about 5%.

6. The process as in claim 4 in which said aqueous plasticizing mediumis water and in whichat least 20% of the total stretch is imparted tosaid filaments by the first of said stretching stem.

7. Aprocess for the manufacture of viscose rayon which comprisesextruding a viscose solution into an acid coagulating bath; withdrawingthe resulting viscose filaments from said bath before they.arecompletely regenerated; stretching said incompletely regeneratedfilaments; treating said stretched filaments with an aqueousplasticizing medium while maintaining said filaments in said stretchedcondition; stretching said treated filaments a second time; transferringsaid stretched filaments to a thread-advancing, thread-storage devicehaving a path of thread travel of progressively diminishing length inthe direction 01' thread travel whereon said incompletely regeneratedfilaments are permitted to shrink an amount less than the amount of saidsecond stretch; and thereafter treating said par-- trially shrunkfilaments with an acid regenerating solution and completing theregeneration of said filaments without permitting substantially anyfurther shrinkage. I

8. The method of producing viscose rayon which comprises extruding aviscose solution into an acidic coagulating bath; withdrawing theresulting viscose filaments from said coagulating bath before they arecompletely regenerated;

passing said filaments to a first thread-advancperiphery ofprogressively diminishing diameter in the direction of thread advancatheperiphery of least diameter having a peripheral speed greater than saidsecond reel whereby said filaments are stretched between said second andthird reels and whereby said filaments are permitted to shrink an amountless than the amount of said first stretch; treating said filamentsstored on.

said third reel with a dilute aqueous acid solution but maintaining saidfilaments in an incompletely regenerated state; passing saidpartiallyshrunk filaments to a fourth thread-advancing, threadstorage reel ofsubstantially uniform diameter; treating said filaments stored thereonwith an acid regenerating solution and completing the regenerationthereof without permitting substantially any further shrinkage.

KENNETH M. McLELLAN.

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